Hydraulic fluid control valves typically include a supply port for communication to a source of pressurized hydraulic fluid and a control port for communication to an end user of the hydraulic fluid. Measurement of the supply port pressure and control port pressure are conducted during calibration of the operation of the fluid control valve.
In the past, measurement of supply or control port pressures has used conventional gage transducers including a vented diaphragm. However, these pressure measurements suffer from inaccuracy as a result of the transducer's not compensating for barometric pressure, which can vary as much as 7 to 8 kPa for example, as well as a result of the transducer's having a very narrow range of linearity over a wide temperature range. Moreover, these transducers are susceptible to migration of foreign matter into the vent passage and resultant contamination of internal electronics.